Scaling foliar respiration to the stand level throughout the growing season in a Quercus rubra forest
Cheng-Yuan Xu (1, 2, 3) and Kevin L. Griffin (1)
1. Lamont Doherty Earth Observatory, Department of Earth and Environmental Sciences, Columbia University, Palisades, NY 10964,
USA / 2. Present address: CSIRO Entomology, 120 Meiers Road, Indooroopilly, QLD 4068, Australia / 3. Corresponding author () / Received February 28, 2007; accepted June 11, 2007; published online February 1, 2008
Summary
Stand-level, canopy foliar carbon loss (Rcan) was modeled for a virtual Quercus rubra L. monoculture at two sites differing in soil water availability in a northeastern deciduous forest (USA) throughout the
2003 growing season. Previously reported foliar respiratory temperature responses of Q. rubra were used to parameterize a full distributed physiology model that estimates Rcan by integrating the effects of season, site and canopy position, and represents the best estimation of Rcan. Model sensitivity to five simplified parameterization scenarios was tested, and a reasonable procedure of simplification
was established. Neglecting effects of season, site or canopy position on respiration causes considerable relative error in
Rcan estimation. By contrast, assuming a constant E0 (a temperature response variable of the respiration model), or a constant night temperature (mean nighttime temperature)
caused only a small relative error (< 10%) compared with the full model. From June 8 to October 28, 2003, modeled Rcan of the virtual Q. rubra monoculture was, on average, 45.3 mmol CO2 m–2 night–1 on a ground-area basis (or 334 mmol CO2 kg–1 night–1 on a biomass basis) and 101 mmol CO2 m–2 night–1 (or 361 mmol CO2 kg–1 night–1) at the drier site and the more mesic site, respectively. To model Rcan of Q. rubra (or other Quercus species with similar respiratory properties), variations in the base respiration rate across season, site and canopy position
need to be fully accounted for, but E0 may be assumed constant. Modeling Rcan at the mean nighttime temperature would not strongly affect estimated canopy carbon loss.
Keywords:
canopy, carbon loss, dark respiration, thermal acclimation.
